From bb85bcb32b0225c3c3fcb44570513c2d085f4f84 Mon Sep 17 00:00:00 2001
From: Nolan Lawson <nolan@nolanlawson.com>
Date: Mon, 28 Oct 2019 08:16:51 -0700
Subject: [PATCH] fix: switch to arrow-key-navigation library (#1607)

For left/right arrow key navigation, switch to a small library I made to
handle this. Also make it load asynchronously, because why not.
---
 package.json                                  |   1 +
 .../observers/leftRightFocusObservers.js      | 123 ++----------------
 src/routes/_utils/asyncModules.js             |   4 +
 yarn.lock                                     |   5 +
 4 files changed, 22 insertions(+), 111 deletions(-)

diff --git a/package.json b/package.json
index 9688e591..64b33491 100644
--- a/package.json
+++ b/package.json
@@ -48,6 +48,7 @@
     "@babel/preset-env": "^7.6.3",
     "@babel/runtime": "^7.6.3",
     "@webcomponents/custom-elements": "^1.3.0",
+    "arrow-key-navigation": "^1.0.1",
     "babel-loader": "^8.0.6",
     "babel-plugin-transform-react-remove-prop-types": "^0.4.24",
     "blurhash": "^1.1.3",
diff --git a/src/routes/_store/observers/leftRightFocusObservers.js b/src/routes/_store/observers/leftRightFocusObservers.js
index 5a8d9009..206b5ee7 100644
--- a/src/routes/_store/observers/leftRightFocusObservers.js
+++ b/src/routes/_store/observers/leftRightFocusObservers.js
@@ -1,123 +1,24 @@
 // Makes it so the left and right arrows change focus, ala Tab/Shift+Tab. This is mostly designed
 // for KaiOS devices.
 
+import { importArrowKeyNavigation } from '../../_utils/asyncModules'
+
+let arrowKeyNav
+
 export function leftRightFocusObservers (store) {
   if (!process.browser) {
     return
   }
 
-  function getDialogParent (element) {
-    let parent = element.parentElement
-    while (parent) {
-      if (parent.classList.contains('modal-dialog')) {
-        return parent
-      }
-      parent = parent.parentElement
-    }
-  }
-
-  function getFocusableElements (activeElement) {
-    const query = `
-    a,
-    button, 
-    textarea, 
-    input[type=text], 
-    input[type=number],
-    input[type=search],
-    input[type=radio],
-    input[type=checkbox],
-    select, 
-    [tabindex="0"]
-  `
-
-    // Respect focus trap inside of dialogs
-    const dialogParent = getDialogParent(activeElement)
-    const root = dialogParent || document
-
-    return Array.from(root.querySelectorAll(query))
-      .filter(element => {
-        if (element === activeElement) {
-          return true
-        }
-        return !element.disabled &&
-          element.getAttribute('tabindex') !== '-1' &&
-          (element.offsetWidth > 0 || element.offsetHeight > 0)
-      })
-  }
-
-  function shouldIgnoreEvent (activeElement, key) {
-    const isTextarea = activeElement.tagName === 'TEXTAREA'
-    const isTextInput = activeElement.tagName === 'INPUT' &&
-      ['text', 'search', 'number', 'email', 'url'].includes(activeElement.getAttribute('type').toLowerCase())
-
-    if (!isTextarea && !isTextInput) {
-      return false
-    }
-
-    const { selectionStart, selectionEnd } = activeElement
-    // if the cursor is at the start or end of the textarea and the user wants to navigate out of it,
-    // then do so
-    if (key === 'ArrowLeft' && selectionStart === selectionEnd && selectionStart === 0) {
-      return false
-    } else if (key === 'ArrowRight' && selectionStart === selectionEnd && selectionStart === activeElement.value.length) {
-      return false
-    }
-    return true
-  }
-
-  function focusNextOrPrevious (event, key) {
-    const { activeElement } = document
-    if (shouldIgnoreEvent(activeElement, key)) {
-      return
-    }
-    const focusable = getFocusableElements(activeElement)
-    const index = focusable.indexOf(activeElement)
-    let element
-    if (key === 'ArrowLeft') {
-      console.log('focus previous')
-      element = focusable[index - 1] || focusable[0]
-    } else { // ArrowRight
-      console.log('focus next')
-      element = focusable[index + 1] || focusable[focusable.length - 1]
-    }
-    element.focus()
-    event.preventDefault()
-    event.stopPropagation()
-  }
-
-  function handleEnter (event) {
-    const { activeElement } = document
-    if (activeElement.tagName === 'INPUT' && ['checkbox', 'radio'].includes(activeElement.getAttribute('type'))) {
-      // Explicitly override "enter" on an input and make it fire the checkbox/radio
-      activeElement.click()
-      event.preventDefault()
-      event.stopPropagation()
-    }
-  }
-
-  function keyListener (event) {
-    if (event.altKey || event.metaKey || event.ctrlKey) {
-      return // ignore e.g. Alt-Left and Ctrl-Right, which are used to switch browser tabs or navigate back/forward
-    }
-    const { key } = event
-    switch (key) {
-      case 'ArrowLeft':
-      case 'ArrowRight': {
-        focusNextOrPrevious(event, key)
-        break
-      }
-      case 'Enter': {
-        handleEnter(event)
-        break
-      }
-    }
-  }
-
-  store.observe('leftRightChangesFocus', leftRightChangesFocus => {
+  store.observe('leftRightChangesFocus', async leftRightChangesFocus => {
     if (leftRightChangesFocus) {
-      window.addEventListener('keydown', keyListener)
-    } else {
-      window.removeEventListener('keydown', keyListener)
+      if (!arrowKeyNav) {
+        arrowKeyNav = await importArrowKeyNavigation()
+      }
+      arrowKeyNav.setFocusTrapTest(element => element.classList.contains('modal-dialog'))
+      arrowKeyNav.register()
+    } else if (arrowKeyNav) {
+      arrowKeyNav.unregister()
     }
   })
 }
diff --git a/src/routes/_utils/asyncModules.js b/src/routes/_utils/asyncModules.js
index 60743c1b..d8308447 100644
--- a/src/routes/_utils/asyncModules.js
+++ b/src/routes/_utils/asyncModules.js
@@ -59,3 +59,7 @@ export const importVirtualListStore = () => import(
 export const importPageLifecycle = () => import(
   /* webpackChunkName: 'page-lifecycle' */ 'page-lifecycle/dist/lifecycle.mjs'
 ).then(getDefault)
+
+export const importArrowKeyNavigation = () => import(
+  /* webpackChunkName: 'arrow-key-navigation' */ 'arrow-key-navigation'
+)
diff --git a/yarn.lock b/yarn.lock
index fcc8ccc5..a2570d5d 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1225,6 +1225,11 @@ array-unique@^0.3.2:
   resolved "https://registry.yarnpkg.com/array-unique/-/array-unique-0.3.2.tgz#a894b75d4bc4f6cd679ef3244a9fd8f46ae2d428"
   integrity sha1-qJS3XUvE9s1nnvMkSp/Y9Gri1Cg=
 
+arrow-key-navigation@^1.0.1:
+  version "1.0.1"
+  resolved "https://registry.yarnpkg.com/arrow-key-navigation/-/arrow-key-navigation-1.0.1.tgz#557f5c0034791acc04091843718888e18c9cd61a"
+  integrity sha512-/RZFi4p3MCr6Y2y2luNh8eP7CwlVsoq+F2oiNoE+jSHgRWUbc+fLaI2/8NWqDF6XZLu5GdTvXkN70KRpN0/5Hw==
+
 asar@^2.0.1:
   version "2.0.1"
   resolved "https://registry.yarnpkg.com/asar/-/asar-2.0.1.tgz#8518a1c62c238109c15a5f742213e83a09b9fd38"